Posted
by
Soulskill
on Monday December 19, 2011 @02:06PM
from the told-you-not-to-drink-all-that-soda-pop dept.

sciencehabit writes "Jupiter is the victim of its own success. Sophisticated new calculations indicate that our solar system's largest planet, which weighs more than twice as much as all of the others put together, has destroyed part of its central core. The culprit is the very hydrogen and helium that made Jupiter a gas giant, when the core's gravity attracted these elements as the planet formed. The finding suggests that the most massive extrasolar planets have no cores at all."

I'm not so sure about everything decaying over time. I thought everything decayed over time to its most-stable state; once a material was in that state, then theoretically it shouldn't decay any more, right?

The most-stable state for carbon is graphite I believe. So diamonds will eventually decay into pencil lead. But once they've turned into graphite, I don't think they'll decay any more.

Through fusion, lighter elements like hydrogen and lithium may be combined (nuclear). This process will provide a net energy output up to "iron."

Through fission, heavier elements may be disassociated (nuclear). This process will provide net energy output down to "iron."

When all you have left is iron, making something else via nuclear methods requires the addition of energy. Thus, "everything decays to iron" represents a lowest energy state from a nuclear perspective. But don't worry, the heat death of the universe [wikipedia.org] won't happen for a long while.

A diamond is a very ordered configuration which will become progressively more disordered. Its configuration may mean that the reactions that alter it (with the oxygen of the air, by example, or even a dislocation of carbon atoms inside the structure) work very slowly, but in the end when these happen there is no turning back.

Yes, but are there wars over cubic zirconia? If I give a stone as a symbol of the love I have for someone, by god, I demand to have lifes on my consience! Besides, there isn't a monopoly artificially keeping up the price of cubic zirconia, so it isn't an effective, yet publically accepted, way to show off my wealth.

You're right that there's no monopoly artificially keeping up the price of CZ, but you can always show off your wealth with stones that are actually rare, and don't need a monopoly to keep their prices up artificially. I believe emeralds are a good example of this. However, I've never heard of any wars over them (nor have I heard the term "conflict emeralds"), so you would be missing out on that by buying them. This is probably why you don't hear much about Emeralds; American women want overpriced stones

You really opened up a can of worms with that. In the responses I see a confusing mixture of the ideas of entropy, disorder and chaos, stellar fusion, and universal heat death, and apparently some people who think these are the same thing? Entropy alone is a huge confusing subject, but to conflate it with these others... well.. that's a whole new ball game.

I believe there is a paper that describes how to trigger a self sustaining fusion reaction in Jupiter's atmosphere. I believe the paper was triggered by 2001 when it came out. I am an ineptly erased slate for anything I experienced prior to 2000 so...

Also, you can't really use the term "weight" for a planetary core. Since the core is at the center of gravity, it has no weight whatsoever. Well, except for towards the Sun, I suppose. Not sure if TFS would be correct or not about the weight in that respect.

You do realize that liquid rock has the exact same mass as solid, right?

That's mostly correct, but as heat is a form of energy and E=mc^2, a rock changed into liquid state would mean that it weighs oh-so-slightly more. For some napkin calculations: the specific heat of iron (at 273 K) is 0.45 J/(K g) meaning that if we had a thousand tons of iron (1E9 g) and increased the temperature 1000 K then the increase of mass would be: 0.45*1E9*1000/(3E8)^2 = 5E-3 g. All that mass and energy for a full 5 milligrams, which is why it's mostly negligible

Disclaimer: I know that the specific heat changes (quite a bit) with temperature but I wanted to keep the example simple.

Did not read the original article, but I would assume that it likely changed it density as well.Meaning that lots of liquid core could have been pushed to the surface making the planet appear bigger and more massive from the outside.

Probably not. The density of the core decreases, but the density remains pretty high. (The pressure is high enough to liquify hydrogen at a reasonable temperature.) And while the core has now disappeared, there is a larger volume of denser liquid.

Besides, what you see when you look at a gas giant is the atmosphere. That's not going to change measurably.

No. It is estimated by the orbits of it's satellites, using Kepler's laws. If you know the period, eccentricity, and size of a satellite's orbit, you can work out the mass of the object that the satellite is orbitting. It has nothing to do with how much of that object is solid.

We "weigh" planets by observing the gravitational force acting on a space craft (whose mass we know) we send close to them. Or by measuring the mass of something else (say by observing a space craft near it) and then observing how it interacts gravitationaly with the planet in question.

You can also do some math with pulsar timings to see periodic errors due to the barycenter of the solar system not being exactly where you thought - which will also give you the planetary masses (well the planet plus th

Yeah you'd have to be an idiot (such as myself) to not see the obvious:

m1 is the mass of the planet. m2 is the mass of the satellite.F = G.m1.m2/r^2 * Thanks Newton.F = m2.a * Thanks Newton again

m2.a = G.m1.m2/r^2a = G.m1/r^2m1 = a.r^2/G

Since we know G and the orbit of the satellite gives us r and a we can determine m1. Of course since the orbit isn't going to be a perfect circle there's some details I can't be bothered to think about:)

weight is really easy to figure out, or what I'm assuming you're talking about, mass, since it produces the easily observable effect of gravity

Remember that "weight" is the effect of gravitational attraction between separate bodies that possess mass. You can't talk about "weight" unless you're referring to at least two objects. (usually with great differences in mass, such as a planet and an object on said planet)

As far as I know, that question was still open to at least some debate. It's hypothesized that there should be a solid core based on the mineral composition and some simulations, but I don't believe there's any direct evidence of it, at least until the mission (mentioned in the article) to measure its gravitational field with an orbiting probe reaches it.

As far as I know, that question was still open to at least some debate. It's hypothesized that there should be a solid core based on the mineral composition and some simulations, but I don't believe there's any direct evidence of it, at least until the mission (mentioned in the article) to measure its gravitational field with an orbiting probe reaches it.

Wouldn't that apply to Earth's core as well? I mean, as far as I'm aware no one has ever drilled all the way to the center of the planet, so what evidence (beyond hypothesis) is there that Earth's core is what we think it is?

There's some evidence beyond only mineral composition for the earth's core, mostly from seismic data; the discontinuities observed in seismic wave travel put constraints on what has to be the case at different layers. At least, it's more data than we have about the interior of Jupiter, which afaik is entirely based on mineral composition and modeling.

There's some evidence beyond only mineral composition for the earth's core, mostly from seismic data; the discontinuities observed in seismic wave travel put constraints on what has to be the case at different layers. At least, it's more data than we have about the interior of Jupiter, which afaik is entirely based on mineral composition and modeling.

Some data comes from detailed magnetic field monitoring, makes sense since it seems to be the cause of the earths magnetic field.

That's nothing compared to being the core of Saturn. You scrub and scrub and scrub and nothing gets rid of those rings, and then Neptune comes home and wants his dinner and doesn't understand that you've been working hard all day. 'Get me a beer!' he hollers as he plops his ass down into the big comfy chair and starts watching Wheel of Fortune.

I tell 'ya, being the core of a planet ain't all wine and roses, I tell 'ya.

âZ"We're pretty sure it has nothing to do with our decision to smash a huge plutonium powered space probe into it or with the resulting huge purple 'second spot' caused by the resulting plume, which was so large it was visible to backyard telescopes and in general was a sort of shocking embarrassment to NASA when it occured."

"No, this disintegration now suddenly occuring just a few years after that incident has nothing to do with us. Jupiter was in the middle of killing itself, anyways. It was only a m

What happens to the silica? From my skimming of TFA, it appears that the experiment only involves the dissolution of the MgO component. There should still be gobs of MgSiO3 (or at the very least SiO2, if the MgSiO3 breaks down into its constituent oxides at the high pressures) hanging around down there.

According to TFA, the MgSiO3 dissociates into SiO2 and MgO under Jovian core conditions. They don't calculate what happens to the SiO2, but assume that its solubility is similar to the MgO component. So that would mean that the SiO2 also goes into solution in the Jovian core.

Also of interest (at least to me) but not addressed in this paper is what happens to the nickel-iron component of the core. Perhaps they figure Jovians don't have enough to worry about, since they form so far from the center of the prot

That's a good point about the iron. There should be some, but at a far lower abundance than the silicates. Still, we're probably talking a few Earth masses of metal (real, actual metal, not what astrophysicists call metal).

I did notice that they speculated that the SiO2 should also dissolve, but I don't really know how valid that assumption is.

My guess is that in the lengthy process that a solar system and/or planet evolves, in which we know nothing about, but can only theorize (as no one has ever lived long enough to see a planet go from a to z), is it possible that there was a core, but the core now has disappeared(on purpose) and that this will create a small vacuum where by the gasses will draw inwards and create a molten core, which in turn will start forming an earth like planet at a much smaller scale, so the large becomes small, and habit

I'm glad to see the shuttle no longer leeching the life out of NASA, but you have to know the cuts go well beyond that. It's not like ditching the shuttle actually freed up more funds for NASA. Bankers need their bonuses far more than we need to do basic science, after all.

Well, let me know when the first spaceship launched by Virgin starts off towards another planet then.

That toy for the rich is just as much of a silly stunt as NASA's cancelled rockets (only a lot cheaper).

For decades, commercial off-the-shelf rockets have been available to launch serious science payloads throughout the solar system. New commercial ventures are bringing lower-cost versions of the same as we speak. At this point, NASA shouldn't be spending a single dime on launch technology. Any such spending only detracts from their scientific goals.

At this point, NASA shouldn't be spending a single dime on launch technology. Any such spending only detracts from their scientific goals.

Well, there is no harm in them spending money on true blue-sky research - the sort of thing that is less likely to get done by a commercial entity. Of course, you can do that with small rockets/etc - you don't need to build huge rockets to test a concept. If they figure out how to get payloads to orbit for $1M or something then maybe they can build a proof-of-concept, though at that price I suspect that private industry would be more than willing to test it out unproven.

That's a large part of the answer right there! The magnetosphere acts as a shield to keep a lot of harmful particles from the solar wind away, things which would work to strip away the atmosphere. Mars is an example of what can happen to planets that lack this. (Obviously, Mars' lower gravity works against it in this regard as well)

What it is high in, are comparatively dense gasses.Sulfuric acidCarbon dioxideEtc.

The solar wind is highly energetic, but is comprised of small atomic mass particles. They lack the kinetic energy to strip away very heavy gasses with strong intermolecular forces. Water, while having strong intermolecular forces, is a very light molecule, and the high energy particles have sufficient energy to break the single covalent bonds that hold it together. This means the cosmic wind rips it apart, and then scours it out into space. Sulfuric acid and cabron dioxide, on the other hand, are very heavy, gravitate deeper into the gravity well, and in the case of co2, have double covalent bonds that are quite powerful. The solar wind doesn't have enough oomph to rip it apart, and the molecules are too heavy to easily blow away.

Mar's armosphere is actually sabotaged by a weak and incomplete magnetic field. It has many small and weak diploles extending from the surface. Under the influence of the solar wind, this actually pinches off large chunks of atmosphere during heavy flares from the sun. This is why mars has such a pronounced atmospheric loss, compared to venus, which doesn't have any discernable mgnetic field at all. If you note, the atmosphere mars does have is comprised of what? Co2.

You should sic Bob [angryflower.com] on him. It's probably not an accurate appraisal, but I always question the education, and maybe even intelligence, of anyone who can't use that simple punctuation mark properly.

What's worse, I see it more and more. Doesn't anyone read books these days?

We know A LOT about the cores of the planets in the solar system from extensive study (including molten, material and other stuff that can be determined from external study). It appears you are talking about examining extrasolar planets. We don't have the capability, and it's doubtful we will, at least in our lifetime. Voyager1 just left the solar system and it's moving at ~35k MPH and it was launched in the 70's, most of the people that designed it are retired or dead and Voyager1 will be dead long before it reaches any other star.

What maintains our atmosphere is the magnetic field generated by the liquid mantle rotating around the core. The magnetic field deflects the solar wind which would blow it off. It's thought by some that Mars lost it's atmosphere and surface water when the liquid mantle cooled and solidified. Mars has no magnetic field.

Which brings up the question: Which will happen first? Earth's core cooling to the point where we lose our atmosphere, or the Sun running out of fuel to the point where Earth can no longer sustain life (as we like it)?

Which brings up the question: Which will happen first? Earth's core cooling to the point where we lose our atmosphere, or the Sun running out of fuel to the point where Earth can no longer sustain life (as we like it)?

The correct answer is neither. Both of those are billions of years in the future. You forgot about a more immediate threat to the planet. Unless something drastic happens, the Human race will have made the earth devoid of life long before that. And even if we don't f' the planet up beyond all fixing, it wont matter because humans will either be extinct or will have colonized the galaxy by then.

Neither. As the sun gets older, it gets brighter (according to wikipedia, about an 10% increase in luminosity every billion years). At some point there will be no more liquid water available because the surface of our planet is too hot. This will happen long before the sun turns into an actual red giant, which in turn will happen long before it runs out of fuel.

The earth's core isn't cooling, AFAIK. Nuclear decay keeps it nice and warm. Of course, that will end gradually, but when it hasn't done so yet, it probably won't be a problem until the sun becomes a red giant.

What maintains our atmosphere is the magnetic field generated by the liquid mantle rotating around the core.

Liquid outer core stirred up by thermal and magnetic turbulence and a solid inner core. The mantle is more-or-less solid.

Mars has no magnetic field.

Now ; it probably had one for a short period early in it's history ; there is some evidence of "magnetic stripes" (and by implication, something resembling sea-floor spreading ?) in the region to the south of the Tharsis volcanoes.(IIRC)

So no one should do a PhD to become the world authority on a subject then? No one should try anything new (let's say, for example, a certain chap's musings on the photoelectric effect or relativity)? And by your numbers even spending 0.001 of a single person's time on something not directly productive should be stopped. So let's ban all art and sports (when you've finished off all pure science research), since I have no time for them. And cooking beyond the purely functional, and interior decoration, an

I never said it robbed anyone of value or their own pet project. I just asked "who the fuck cares?" So far, no one has answered whether or not they cared, just objected to my question. Questions are not evil. You and others have drawn too many conclusions from my question.

Now I see that you did. Usually when someone replies with a long-winded "fuck you" I don't read past the first few parts of the "fuck you." You accuse me of narrow-mindedness, but not thinking an extremely narrow-view is of interest is not narrow-mindedness. I will not be following your advice to not post; when I have something to say, I will say it; even if you don't like it.

Well, "we" didn't get there. "We" haven't gone beyond the far end of a low moon orbit a very few times. And we haven't extended our reach in over 40 years. Spacecraft that we built have gone farther. It seems a distinction worth making to me; maybe it's silly. When man ceases to explore in person, and that day may have arrived permanently, he will be something different, in my mind.